Infold carton with corner bracing strut



March l, 1960 W. M. STRANGE INFOLD CARTON WITH CORNER BRACING STRUT Filed Aug. 30, 1957 INFOLD CARTON WITH CORNER BRACING STRUT William M. Strange, Neenah, Wis., assignor to John Strange Carton Co., Inc., Menasha, Wis., a corporaftion of Wisconsin Application August 30, 1957, Serial No. 681,256

3 Claims. (Cl. 229--32) This invention relates from the general aspect to infold cartons and more particularly to an infold carton having a corner bracing strut extending diagonally across the corner in substantially horizontal position.

lnfold cartons have in the past been developed which have attempted to prevent collapsing of the corners therel of although for the most part these have not proved to be satisfactory. In the present invention I have provided an infold type carton which enables the manufacturer to produce imperforate bottom and side walls and yet will produce positive means for holding the corners in fully expanded relation.

It is an object of my present invention to provide an infold type carton wherein a bracing strut disposed entirely Within the carton is provided to securely and positively retain the sides of the carton in opstanding relation.

More specifically it is an object to provide an infold type carton wherein a pair of corner anchoring ilaps are provided on the respective sides and ends and wherein a bracing strut is integrally formed in connection with one of said flaps and underlies the other iiap in sliding relation thereto when in collapsed position but snaps out into substantially horizontal bracing position when the carton is initially opened.

These and other objects and advantages of my invention will more fully appear from the following description, made in connection with the accompanying drawings, wherein like reference characters refer to the same or similar parts throughout the several views, and i which:

Fig. 1 is a top plan view of a blank from which my new carton is constructed;

Fig. 2 is a fragmentary perspective view showing the sides in partially collapsed position;

Fig. 3 is a perspective view showing the tray of a carton in fully expanded operative position;

Fig. 4 is a fragmentary perspective view showing a carton corner in partially collapsed position;

Fig. 5 is an enlarged fragmentary perspective view showing a carton corner held in fully expanded operative position;

Fig. 6 is a fragmentary perspective view of a carton corner in collapsed position; and

Fig. 7 is a vertical sectional View taken substantially i along the line 7-7 of Fig. 6.

As illustrated I provide an infold tray type carton having a bottom panel 10 with a pair of spaced apart parallel fold lines 11 formed along the sides edges thereof. A pair of carton sides 12 are integrally formed with the bottom 10 and are hinged thereto along said fold lines 11. A pair of carton ends 13 are also integrally formed with said carton bottom 10 and are hinged thereto along fold lines 14.

A pair of anchoring flaps 13a extend outwardly from the ends of end panels 13 and are hinged thereto along the fold lines 13b. These flaps 13a are in the form shown disposed only adjacent the upper portion of said end ilaps 13 and a pair of side anchoring aps 12a are United States Patent i 2,926,831 Patented Mar. 1, l 960 formed from the sheet material between the ends of the srde panels 12 and the lower edges of flaps 13a and are hlnged to the lower end portions of the respective side panels along the fold li'ne 12b. A bracing strut 15 is integrally formed with the upper edge of each iiap 12a and is hinged thereto along a fold line 15a. The lower edge portion of the iap 12a is cut away as indicated at 12C of Fig. l to prevent bunching at the corners when the carton is in folded collapsed position.

A pair of diagonal fold lines 12d extend from the respective corners of the bottom panel 10 across the ends of said side panels 12 at substantially 45 to the fold lines 11 thus forming generally triangular attachment portions 12e to which the flap 13a is securely adhered along the upper marginal portion thereof as best shown in Fig. 5. The lower marginal portion of the flap 13a must be free and unattached with respect to the side panel12 to permit the triangular bracing strut 15 to be slidably received thereunder when in collapsed position as best shown in Figs. 6 and 7.

The attachment or anchoring aps 12a is of course secured to the inside of the adjacent end 13 as by being glued thereto and the bracing strut 15 integrally connected with the upper edge of ap 12a along fold line 15a is slidably received under the end anchoring liap 13a as indicated when the carton is in collapsed position.

When the carton is opened into operative position the shifting of the end panels 13 into upstanding relation pulls the diagonal bracing strut 15 out from under the lower portion of attachment flap 13a to position said strut in substantially horizontal position extending diagonally across the corner portion of the box. The side edge of the bracing strut when in corner locking position abuts the inside surface of the side panel 12 as shown in Figs. 3 and 5 and the lower edge of anchoring ap 13a overlies the extreme side marginal edge portion of said strut 15 to positively hold the same in locking position.

it will be seen that I have provided a relatively simple yet highly eicient infold box construction having a corner locking bracing strut which will automatically snap out into operative position to positively hold the corner from collapsing'after the same has been fully opened. It will be apparent that the bracing strut will also serve to provide a support for a divided platform or panel 16 which may be desirable across the central portion of the box tray as indicated in Fig. 3 so as to divide the box horizontally into two separate sections.

#lt will, of course, be understood that various changes may be made in the form, details, arrangement and proportions of the parts without departing from the scope of my invention which consists of the matter shown and described herein and set forth in the appended claims.

What is claimed is:

1. An infold carton comprising a bottom having fold lines along the sides and ends thereof, side and end panels respectively hinged to and extending outwardly from said bottom at said fold lines, a pair of corner attachment flaps formed on said panels at each corner, each of said flaps being secured to the inner surface of the adjacent panel, each of said pairs of flaps comprising an upper and a lower flap, the upper edge of the lower flap lying in substantially the same plane as the lower edge of the upper ilap, the panels carrying said lower flaps being provided with diagonally disposed fold lines extending from the corners of said bottom across the end portions of said panel at substantially 45 degrees to the bottom fold line to form generally triangular attachment portions to permit compact collapsing of the panels against the bottom, corner bracing struts hingedly connected to said lower flaps and tensioned for biased upward movement to at least substantially horizontal position, said corner struts having a disconnected marginal edge cooperatively engaging the inner surface of said triangular attachment portions and an upper surface contiguous to and underlying the lower edge of said upper flap when the carton is in an open upright condition.

2. The structure set forth in claim 1, wherein the lower portion including the lower edges of the upper flaps adjacent the corner struts are unattached and form strut receiving pockets between said aps and the panels to which they are secured, which pockets removably and slidably receive said corner struts when the carton is in 10 2,324,151

collapsed position.

3. The structure set forth in claim 1 wherein said corner bracing struts form horizontal supporting elements for a horizontal divider partition extending across the open area ofthe carton.

References Cited in the ile of this patent UNITED STATES PATENTS 1,195,758 Wilson Aug. 22, 1916 Hoag July 13, 1943 2,424,716 Smart July 29, 1947 

